This cohort study is designed to measure the risks and benefits of menopausal estrogen replacement therapy (ERT) in terms of incidence disease and mortality (of endometrial cancer, breast cancer, hip fracture, and acute myocardial infarction); to study the effect of dietary and supplemental intake of vitamin A on the development of epithelial cancer, especially lung cancer, especially lung cancer; and to evaluate the risks and benefits associated with other health-related practices in older adults. Detailed health surveys have been collected on 12,410 residents of Leisure World Laguna Hills (Cohorts I,II,III) and those from recent move-ins (Cohort IV) are now being obtained. The questionnaire covers basic demographic information, medical history, personal habits, medical screening, vitamin usage, and (for women) menstrual and reproductive histories including use of hormone replacement therapy. Followup questionnaires were sent to all living members of Cohorts I and II in 1983 and to those of Cohorts I, II and III in 1985. Non-respondents to this most recent mailing are being telephoned to encourage continued participation in this study and those lost to followup traced for a current address. Additional followups will be conducted utilizing the same procedures in January 1988 and September 1990. Abstraction, coding and data entry of hospital discharge diagnoses (from three local hospitals), cancer pathology reports (from five local hospitals), and death certificates are ongoing and will continue throughout the funding period. The data from this cohort study will be regularly analyzed and prepared for publication. In particular, we will evaluate the modifications in risks of individual disease (endometrial and breast cancers, osteoporotic fractures, coronary heart disease, gallbladder disease) associated with different doses, durations, and timing of ERT, and the potential confounding and modifying effects of other factors such as weight, previous disease, and age at and type of menopause. In addition, the relationship between certain life-style practices (such as exercise, weight, analgesic use, alcohol consumption, smoking, vitamin supplementation, and the intake of certain food items) and certain chronic diseases will be assessed.